1. Field of the Invention
The invention relates to a sheet-type β-FeSi2 element, which is in connection with technical fields of semiconductor element devices such as an optical sensor, a solar cell and a thermoelectric conversion element in electronics fields and uses an new semiconductor material, and a method and an device for manufacturing the element in a simple way.
2. Description of the Prior Art
In a previous semiconductor device, a functional thin film is formed as a material on a silicon (Si) substrate, a GaP substrate, a GaAs substrate, and a ceramic flat base material, an electrode for input and output of electric signals is formed on the film, using a photolithography technology and vacuum processing, and a light-antireflection protective film is manufactured, using vacuum processing.
Recently, there has been proposed and developed use of a β-FeSi2 semiconductor device comprising a material which is rich as one of earth resources and has less environmental load. Many of methods for forming a junction film by using the above material are executed by vacuum processing such as a laser ablation method, an ion implantation one, a molecular beam epitaxy one, and vacuum deposition one. On the other hand, there has been proposed a method in which not a previous metal film deposition method, but a method using an effect by conversion into a metallic crystal phase at a high temperature peculiar to a β-FeSi2 material is used for forming the electrode, and problems caused by the photolithography technology for forming a metal electrode are solved by a laser annealing method (Japanese Patent Application No. 2001-157087, 2001-235664). Moreover, a previous technique using SiO2 in a process for forming a film in a vacuum has been applied for forming a light-antireflection protective film.
There have been the following problems in each step of a previous method for manufacturing an element:    (1) Use of single crystal Si for a substrate of an element increases the price, and high material and manufacturing costs are caused by use of the single crystal Si for a case in which an element is required to be manufactured with an extremely low price, for example, for manufacturing a solar cell;    (2) When a polycrystalline silicon substrate is used, it is difficult to obtain the enough amount of a so-called low grade Si scrap, which is a raw material for a polycrystalline silicon substrate, with a high impurity concentration;    (3) When a semiconductor junction layer with good characteristics is formed, using Si and compounds, the throughput is low and the cost is high because an expensive device for advanced control of growth in a high vacuum is required to be used;    (4) When the photolithography technology for forming a metal film and the laser annealing method are used for forming an electrode, an expensive device is required to be used, and the high throughput cannot be obtained; and    (5) When a vacuum process is used for forming a light-antireflection protective film, the device cost becomes high, and the throughput is limited by the internal volume of the device.